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CRTEmudriver & VGA2SCART vertical overscan on PAL CRT

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akki007:
New here, I rescued a Toshiba 2112db from the recycling place. It had some vertical fold issues but its been fixed and it looks ace. Here's my boggle...

1. If I connect a Wii using scart or composite, I get a perfect image, no overscan.
2. If I connect a DVD player, same, no overscan

So I dont want to adjust the V size/position (its manual, not in the service menu)

3. If I connect an old PC (AMD R5 430) using CRTemudriver and VGA2SCART, I get:

* Vertical overscan on 288p
* black bars on 240p
I'd like to have the desktop at 576i, but for some reason it wont let me add a 576i resolution to ArcadeOSD, I mean I can add the modeline, but it wont show up to use.

Basically, my question is... how on earth do I get a resolution that fills the screen, and is higher than 240p so I can switch back down in retroarch for gaming, but use the desktop!!
 

Zebidee:
You need to post this on the "Groovymame" branch. Before you do that, read the stickied threads especially the one on monitor presets: https://forum.arcadecontrols.com/index.php/topic,116023.0.html

You can experiment with different monitor presets to reduce over/underscan. The defaults provided are "safe" for most, but I find they need tweaking to suit different CRTs. Especially the front/backporch values. To get around different geometries between PAL & NTSC, I use a monitor preset with two sets "crt_range" values, one optimised for ~50hz and the other for ~60hz.

Arcade games are designed as single games for arcade monitors, which can be easily adjusted (with pots) to 100% fill the screen. TVs usually have some overscan built in, typically 2-10% of the picture is off-screen. Adjusting geometry is typically harder for TVs, but overscan can usually be reduced by service menu adjustments or even pots. Some TVs will have different adjustments for NTSC vs PAL.

By comparison, Wiis were made to be used with CRT TVs, so they already took overscan into account when designing the video modes and the games themselves.

buttersoft:
Also, because i don't want to retype it... And this applies to your modelines in general, it's not just for GM.


--- Quote from: buttersoft on January 01, 2024, 04:47:23 pm ---there is a guide to VMM and ArcadeOSD - http://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=46

VMM sets up modelines and installs them. ArcadeOSD adjusts them. And you can save the adjustments. But the switchres utility in GroovyMAME, which is where the magic happens, uses the timings in the mame.ini file. When playing with ArcadeOSD, remember that Esc will back out of any changes.

To make adjusted timings stick for GM you can either redo VMM with updated timings in the monitor.ini, or instead you can just edit the mame.ini file with the updated horizontal timings (starting with the crt_range0 line, which for the generic_15 monitor preset defaults to crt_range0 15625-15750, 49.50-65.00, 2.000, 4.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 288, 448, 576 - remember that your monitor may want a different preset, and that any specific vertical.ini, machine.ini like neogeo.ini, or game.ini files will override). Calamity insists redoing VMM works best, but i find that with the spread of modes i'm using (230p at 60Hz all the way up to 600i at 50Hz) on different monitors, i still want to set the mame.ini timings afterward. There's a bit about vertical sizing/timings by Calamity here.

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